Hot Days Research Articles

RELATING WEATHER TRENDS AND RESIDENCE LENGTH TO LOCAL CLIMATE CHANGE CONCERNS IN KNOXVILLE, TENNESSEE

ABSTRACT Climate change beliefs and concerns are closely tied to socio-demographic traits and personal experience with extreme weather events. Here, we compare survey participants’ perceptions of extreme weather trends in Knoxville, Tennessee, with observed trends in extreme weather during their residency. We also assess the relationship between climate change concerns and weather perceptions. We find that perceived weather trends, including hot summer days and cold/snowy winters, matched observed trends for some—but not all—residents, depending in part on the length of their residency. Perceived weather trends were also related to level of climate change concerns, belief in its anthropogenic nature, and some socio-demographic characteristics, including income. Our results suggest that as cities in the Southeast continue to grow in population and residents experience the effects of Earth’s changing climate, these factors will play an important role in extreme weather perceptions and attribution to climate change.

Evaluating the Impact of Trees on Residential Thermal Conditions in Los Angeles Using Community Science

As the planet warms, heat-vulnerable communities in cities face increased heat-related risks including lost productivity, reduced learning outcomes, illness, and death. Despite the growing threat of heat, effective approaches to alleviate urban heat are available. Tree planting has received investment in a growing number of cities around the world, but there are significant gaps in our understanding of the cooling potential of trees in the urban context, particularly the impacts on indoor spaces where urban dwellers spend most of their time. Our study engaged community scientists in Los Angeles County, USA to collect data on the impacts of trees on indoor and outdoor thermal conditions in residential sites. Participants created a thermal sensor network that contributed continuous readings for the study period. We mimicked an experimental research design using a difference-in-differences approach where “treehouses” with more trees and “non-treehouses” with fewer trees were compared on hot days (>90°F or 32°C) and non-hot days. We found that on hot days indoor temperatures in treehouses warm less than in non-treehouses, but that trees provide relatively less benefit at night. We also found that exposure to extreme heat reaches dangerous levels in older residences without trees or air conditioning. underscoring the need for swift action to cool heat-vulnerable communities.

Thermal management of PV panel through the circulation of a nano-MgO/water-based nanofluid

Since conventionalfossil fuels are used up at the extreme, alternate sustainable greenenergy sources become more popular for producing power. Among the most common ways to produce power is using solarPVtechnology. However, a s a result of overheating of the panels, the efficiency of PV panels drops during the hot sunny days all overthe year, owing tothe peak irradiance of thesun. Hence, solar PV’sefficiency may be increased throughthe right cooling system by reducing the PVtemperature. To alleviate the problems caused by the overheating of the solar panels, this currentstudy investigates the potential of using a nanofluid based on nano-MgO/water. The nanofluid has been synthesizedby dispersing MgOnanoparticlesat a concentration of 0.3% in thewater after distillation. After a whole dayof investigation, the temperature of the solar PVusing nano-MgO/waternanofluid had been noticed as 35 °C, in contrastthe temperature of the conventional PVpanel was found as 78 °C. In addition, the minimized temperature differences through the deployment of nano-MgO/waternanofluid also led to a 16.9% enhancementin overall electrical efficacy of the panel.

Hourly analysis of temperature and heat gain reduction for building envelope-compacted phase change material in extremely hot conditions

Compacting phase change materials (PCMs) for thermal energy management in buildings is a promising method to reduce peak temperature and heat gain in hot climates. This experimental study analyses the hourly temperature reduction (HTR) and hourly heat gain reduction (HHGR) of building envelope-compacted PCM passively during a hot summer day. Two cubicles, one compact with PCM and the other without, are fabricated and examined under non-ventilated conditions concerning the supreme PCM thickness and position in the roof and the best thermally-performed PCM-bricks in the walls. The results showed that PCM effectiveness is time-dependent, and the east wall performed better than the other walls showing a maximum HTR of 9.1 % and HHGR of 16 %. Moreover, the PCM roof surface showed a maximum HTR and HHGR of 15.1 % and 34.9 %, respectively, contributing to the total HGR by one-third. The research exhibited that the PCM cubicle indoor temperature was reduced by up to 4 °C in comparison with the one referenced.

Working under the 2021 Heat Dome: A Content Analysis of Occupational Impacts Mentioned in the Canadian Media.

Extreme heat events directly impact worker health and cause additional cascading and transitional workplace impacts. However, current investigations on these impacts often rely on specific datasets (e.g., compensation claims, hospitalizations). Thus, to continue to work towards preventing and mitigating the occupational risks posed by extreme heat events, this study aimed to explore the occupational impacts of the 2021 Heat Dome in Canada using a qualitative content analysis method on a news-based dataset. A systematized review of news articles published before, during, and after the 2021 Heat Dome was conducted on academic (n = 8) and news (n = 5) databases, along with targeted grey literature. Two researchers qualitatively coded the articles in NVivo for occupational impacts or references mentioned within the articles. Overall, 52 different occupations were identified as being impacted by the 2021 Heat Dome. Impacts were diverse and ranged from work cancellations or delays to work modifications and reports of heat-related illnesses. The 2021 Heat Dome impacted the health and safety of many occupational groups and provided new insights into the expanding impacts that extreme heat events can have on the Canadian workforce. With climate projections showing a growing trend of more hot days and intense heat waves in Canada, addressing these concerns should be a critical priority.

Future heat extremes and impacts in a convection-permitting climate ensemble over Germany

Abstract. Heat extremes and associated impacts are considered the most pressing issue for German regional governments with respect to climate adaptation. We explore the potential of a unique high-resolution, convection-permitting (2.8 m), multi-GCM (global climate model) ensemble with COSMO-CLM (Consortium for Small-scale Modeling Climate Limited-area Modelling) regional simulations (1971–2100) over Germany regarding heat extremes and related impacts. We find a systematically reduced cold bias especially in summer in the convection-permitting simulations compared to the driving simulations with a grid size of 7 km and parametrized convection. The projected increase in temperature and its variance favors the development of longer and hotter heat waves, especially in late summer and early autumn. In a 2 ∘C (3 ∘C) warmer world, a 26 % (100 %) increase in the heat wave magnitude index is anticipated. Human heat stress (universal thermal climate index (UTCI) > 32 ∘C) and region-specific parameters tailored to climate adaptation revealed a dependency on the major landscapes, resulting in significantly higher heat exposure in flat regions such as the Rhine Valley, accompanied by the strongest absolute increase. A nonlinear, exponential increase is anticipated for parameters characterizing strong heat stress (UTCI > 32 ∘C, tropical nights, very hot days). Providing region-specific and tailored climate information, we demonstrate the potential of convection-permitting simulations to facilitate improved impact studies and narrow the gap between climate modeling and stakeholder requirements for climate adaptation.

How Much Will Climate Change Reduce Productivity in a High-Technology Supply Chain? Evidence from Silicon Wafer Manufacturing

The frequency of hot days in much of the world is increasing. What is the impact of high temperatures on productivity? Can technology-based adaptation mitigate such effects of climate change? We provide some answers to these questions by examining how high outdoor temperatures affect a high-technology, precision manufacturing setting. Exploiting individual-level data on the quantity and quality of work done across 35,190 worker-shifts in a leading NYSE-listed silicon wafer maker in China, we evidence a negative effect of outdoor heat on productivity. The effects are large: in our preferred linear specification, an increase in wet bulb temperature of 10,^{circ }C causes a reduction in output of 8.3%. Temperature effects exist even though the manufacturer’s work-spaces are indoors and protected by high-quality climate control systems. Results are not driven by extreme weather events and are robust to alternative modelling approaches. They illustrate the potential future adverse economic effects of climate change in most of the industrialised world.

550 CSF Leak or Ear Wax? Logical Thinking in Emergency Management of a Collapsed Patient with Heat Stroke

Abstract A man in his 60s presented to RESUS by ambulance on the hottest day of the year with suspected STEMI and collapse at home. The patient was intubated and unresponsive (GCS 5), with global rigors. Hospital ECG showed sinus tachycardia. Body temperature was in excess of 41°C, confirmed on central temperature monitoring. Bilateral clear fluid was noted to be discharging from both ear canals. Query CSF leak was indication for CT head, which was unremarkable. Considering this, efforts were focused on optimising body temperature. This was done with the use of ice packs and fans as well as continuous misting of cool water over the exposed patient. Improvement was shown with temperatures decreasing to 38°C. In questioning the cause of the “clear fluid,” a swab of it placed on an icepack swiftly returned the fluid to its natural consistency of ear wax. As a result of the extraordinarily high body temperatures, ear wax had melted in both ear canals and started to leak out, giving the impression of a CSF leak. This was simply identified at the bedside to refute the idea of a CSF leak. As CSF leak was the indication for a CT head, this could have been avoided with rapid cooling initiated earlier. Unfortunately, this patient later died due to heat stroke. Whilst avoiding the delay of a CT head most likely would not have changed the prognosis for this patient, it is useful to note the importance of logical thinking in an emergency setting.

Behavioural thermoregulation and food availability drive fine‐scale seasonal habitat partitioning in limpets

Abstract Small‐scale spatial variation in temperature plays a key role in limiting the distribution of organisms in thermally heterogeneous environments. In the rocky intertidal zone, intra‐day temperature variation at small scales (cm–m) can easily exceed 30°C. To experimentally test the impact of this small‐scale temperature heterogeneity on the distribution of an ecologically important limpet species (Cellana denticulata), boulders on an intertidal rocky reef in New Zealand were rotated and small‐scale temperature variability and food availability were measured throughout 1 year. Small‐scale variability in thermal tolerance, heart rate and heat shock protein expression was also measured to relate in situ limpet distributions with environmental conditions. Temperature variability was measured using limpet bio‐mimics and HOBO pendant temperature loggers, while food availability (chlorophyll a concentration) was measured on in situ concrete fibreboard tiles. To measure limpet distributions, every tagged limpet on each of 18 boulders was followed from June 2021 to 2022. During each sampling, the location of each limpet, compass direction and slope of the surface that each limpet inhabited was measured. To test for physiological differences among limpets from each microhabitat, thermal tolerance and heat shock protein expression were measured in collected limpets; in situ heart rates and body temperatures were also measured sporadically on hot days. Maximum predicted body temperatures (36–39°C), heart rates and actual body temperatures were greatest on equatorial surfaces (i.e. surfaces facing the equator) whereas food availability was greatest on poleward‐facing surfaces. During summer, limpets moved towards surfaces that minimised their body temperatures and maximised food availability, namely vertical and poleward‐facing surfaces and undersides of boulders. Thermal tolerance, measured using Arrhenius breakpoint temperatures (mean ± SE: 34.7–35.8 ± 0.4–0.7°C) and flat line temperatures (36.2–37.4 ± 0.3–0.4°C), was similar among limpets facing different directions. Surprisingly, heat shock protein expression was relatively consistent throughout the year and among directions. Overall, limpet populations are resilient to thermal stress because they effectively use behavioural thermoregulation to exploit cooler microhabitats that also have greater food availability during summer. Read the free Plain Language Summary for this article on the Journal blog.

Analyzing Extreme Temperature Patterns in Subtropical Highlands Climates: Implications for Disaster Risk Reduction Strategies

This study utilized hot and cold indices to evaluate the changes in extreme temperature events that occurred in subtropical highland climates from 1991 to 2020. The modified Mann–Kendall (MMK) test and the Theil–Sen (TS) slope estimator were used to analyze the linear trends in the time series of the extreme temperature indices. The northern highlands of Pakistan (NHP) were considered as a case study region. The results showed that the annual maximum temperature had a slightly increasing tendency (at the rate of 0.14 °C/decade), while the annual minimum temperature had a slightly decreasing tendency (at the rate of −0.02 °C/decade). However, these trends were not significant at the 5% significance level. The decadal averages of the hot indices were the highest in the second decade (2000s), while they were the lowest in the subsequent decade (2010s). In comparison, all the cold indices except the annual minimum value of the maximum temperature (TXn) showed a persistent decline in their decadal averages throughout the 2000s and 2010s. Overall, the frequency of hot days significantly increased in the NHP during the study period. This study found that the hot days and coldest days increased over the past three decades in the NHP. However, there was a decreasing trend in the cold spell duration, cold nights, and the coldest nights over the past three decades, as demonstrated by the trends of the cold spell duration index (CSDI), the temperature of cold nights (TN10p), and the annual minimum value of the minimum temperature (TNn) indices. These changes may impact the environment, human health, and agricultural operations. The findings provide useful insights into the shifting patterns of extreme temperature events in northern Pakistan and have crucial implications for the climate-change-adaptation and resilience-building initiatives being undertaken in the region. It is suggested that the continuous monitoring of extreme temperature events is necessary to comprehend their effects on the region and devise strategies for sustainable development.

Adaptive predictive control of a fan-ventilated tunnel greenhouse with evaporative cooling

In the present work, micro-climate control of a fan-ventilated tunnel greenhouse with evaporative cooling is investigated via simulation study. For this purpose, the adaptive generalized predictive control (AGPC) strategy is adopted to control temperature, relative humidity, and CO2 concentration in the greenhouse on extremely hot summer days. A dynamic model which integrates a distributed model of greenhouse micro-climate with a crop growth model is used for numerical simulation of the tunnel greenhouse. The controller performance is analyzed via numerical simulation. The relative gain array analysis confirms that greenhouse micro-climatic parameters are highly interactive. However, simulation results showed that AGPC can efficiently handle variables interaction and follow set-points despite actuator limitations and high outside temperature. Besides, by considering output constraints in applying AGPC, the control system can keep the humidity of the greenhouse in a specific range instead of in a particular set point. The calculation burden for the AGPC strategy is kept low without increasing prediction error by employing a linear model and on-line adaptive identification. The applied strategy can handle the uncertainty of the design model due to the model mismatch by on-line identification of model parameters using the recursive least square method.

Perceptions of the health risk from hot days and the cooling effect of urban green spaces: a case study in Xi'an, China.

Hot days are one of the typical threats to human health and sustainable cities. The exploration of residents' perceptions of thermal environment and its mitigation measures will support the health risk prevention. A survey with a combination of closed-ended and open-ended questions was conducted in July 2021 among 13 urban parks in Xi'an City, China. With the help of ANOVA and ordinal logistic regression, this study investigated the influencing factors both on residents' health risk perception of hot days and their perception of the effect of urban ecological landscape on reducing the thermal risk. The relationship between health risk perception and residents' needs of urban ecological construction was also explored. According to 325 valid questionnaires, the male-female ratio of respondents was found to be 1:0.87, young people aged 18-29 (26.46%), the retirees (27.08%) and the ones with undergraduate education (33.23%) were, relatively, the largest groups. The results show that 92.31% of the respondents believed that their daily lives were under the influence of hot days. Housing types, occupation, cooling equipment at work, and outdoor working hours all had a significant impact on their high temperature perceptions. The proportion of respondents who were under a huge health risk and sought medical treatment due to hot days was 30.16% and 44.92%, respectively. Women were 18.52 and 2.33 times more likely to suffer health threats and experience discomforts than men. Furthermore, 73.23% of the respondents believed that the urban ecological landscapes in Xi'an had an enhanced cooling effect in recent years. Compared with the morphological characteristics, residents' recognition of the restriction of landscape's area on its cooling effect was higher, and the residence duration showed a significant influence. The cooling effect of green spaces and water effectively resisted urban thermal threats, and residents' needs of the urban ecological landscapes was associated with their health risk perceptions of hot days. In the future, it is necessary to promote the early warning of hot days, meanwhile, the optimization of landscape patterns of green infrastructures should be implemented in urban planning for the purposes of residents' health risk prevention.

Diurnal Temperature Range and Its Response to Heat Waves in 16 European Cities—Current and Future Trends

An important indicator of climate change is the diurnal temperature range (DTR), defined as the difference between the daily maximum and daily minimum air temperature. This study aims to investigate the DTR distribution in European cities of different background climates in relation to the season of the year, climate class and latitude, as well as its response to exceptionally hot weather. The analysis is based on long-term observational records (1961–2019) coupled with Regional Climate Model (RCM) data in order to detect any projected DTR trends by the end of the 21st century under intermediate and high emission greenhouse gases (GHGs) scenarios. The analysis reveals marked variations in the magnitude of DTR values between the cities, on the one hand, and distinct patterns of the DTR distribution according to the climate class of each city, on the other. The results also indicate strong seasonal variability in most of the cities, except for the Mediterranean coastal ones. DTR is found to increase during hot days and heat wave (HW) days compared to summer normal days. High latitude cities experience higher increases (3.7 °C to 5.7 °C for hot days, 3.1 °C to 5.7 °C for HW days) compared to low latitude cities (1.3 °C to 3.6 °C for hot days, 0.5 °C to 3.4 °C for HW days). The DTR is projected to significantly decrease in northernmost cities (Helsinki, Stockholm, Oslo), while it is expected to significantly increase in Madrid by the end of the 21st century under both the intermediate- and high-emission scenarios, due to the asymmetric temperature change. The asymmetrical response of global warming is more pronounced under the high-emission scenario where more cities at higher latitudes (Warsaw, Berlin, Rotterdam) are added to those with a statistically significant decrease in DTR, while others (Bucharest, Nicosia, Zurich) are added to those with an increase in DTR.

Cool, dry nights and short heatwaves during growth result in longer telomeres in temperate songbird nestlings.

Exposure to rising sublethal temperatures can affect development and somatic condition, and thereby Darwinian fitness. In the context of climate warming, these changes could have implications for population viability, but they can be subtle and consequently difficult to quantify. Using telomere length (TL) as a known biomarker of somatic condition in early life, we investigated the impact of pre-hatching and nestling climate on six cohorts of wild nestling superb fairy wrens (Malurus cyaneus) in temperate south-eastern Australia. Models incorporating only climate information from the nestling phase were best supported compared to those including the (pre-)laying to incubation phase (previously shown to affect mass) or both phases combined. This implies that nestling TL is most sensitive to ambient climate in the nestling phase. The top model showed a negative relationship between early-life TL and nestling mean daily minimum temperature when rainfall was low which gradually became positive with increasing rainfall. In addition, there was a positive relationship between TL and the frequency of hot days (daily maximum temperature ≥35°C), although these temperatures were rare and short-term. Including other pre-hatching and nestling period, climate variables (e.g., mean daily maximum temperature and mean diurnal temperature variability) did not improve the prediction of nestling TL. Overall, our results suggest that cooler nights when conditions are dry and short-term temperature spikes above 35°C during development are conducive for somatic maintenance. While these findings indicate a potential pathway for climate warming to impact wildlife fitness, they emphasize the need to elucidate the mechanisms underlying these complex associations.

Crowdsourcing air temperature data for the evaluation of the urban microscale model PALM—A case study in central Europe

In summertime and during heat events the urban heat island can negatively impact human health in urban areas. In the context of climate change, climate adaptation receives more attention in urban planning. Microscale urban climate modelling can identify risk areas and evaluate adaptation strategies. Concurrently, evaluating the model results with observational data is essential. So far, model evaluation is mostly limited to short-term field campaigns or a small number of stations. This study uses novel crowdsourcing data from Netatmo citizen weather stations (CWS) to evaluate the urban microscale model PALM for a hot day (Tmax ≥ 30°C) in Bochum in western Germany with anticyclonic atmospheric conditions. Urban-rural air temperature differences are represented by the model. A quality control procedure is applied to the crowdsourced data prior to evaluation. The comparison between the model and the crowdsourced air temperature data reveals a good model performance with a high coefficient of determination (R2) of 0.86 to 0.88 and a root mean squared error (RMSE) around 2 K. Model accuracy shows a temporal pattern and night-time air temperatures during the night are underestimated by the model, likely due to unresolved cloud cover. The crowdsourced air temperature data proved valuable for model evaluation due to the high number of stations within urban areas. Nevertheless, weaknesses related to data quality such as radiation errors must be considered during model evaluation and only the information derived from multiple stations is suitable for model evaluation. The procedure presented here can easily be transferred to planning processes as the model and the crowdsourced air temperature data are freely available. This can contribute to making informed decisions for climate adaptation in urban areas.

Spatiotemporal Variability of Hot Days in Association with the Large-Scale Atmospheric Drivers over Vietnam

The severe heatwaves and hot spells in Vietnam were observed more frequently in intensity and duration due to global warming and climate change impacts. The hot days and extreme summer events make the weather harsh and significantly affect human health and the environment. This study presents the spatiotemporal distribution of the number of hot days (NHDs) in Vietnam. The variability of NHD in seven climate subregions is also examined in association with the large-scale drivers. The European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis version 5 (ERA5) data for the period 1981–2020 are used. Principal component analysis is also applied to the observed monthly NHD to obtain spatial patterns and time series. The results show that the NHD in the Highland and South subregions from March to May is linked with the subtropical high associated with decreased 500hPa-level vertical velocity (VV500). From May to June, the North and Central subregions seem related to deepening the Asiatic low and enhancement of southwest flows across the Indochina Peninsula. Finally, both increased southwest flows and decreased VV500 can partly contribute to the intensification of NHD in the North and Central subregions during July and August. The long trends of NHD are also examined. The results reveal that the increasing trends in NHD occur in most subregions, except for the Central Highland, and changing trends of NHD in June greatly contribute to the annual trend of NHD. Finally, the examinations with the El Niño-Southern Oscillation events show that NHD is significantly higher in El Niño events than in La Niña events in March and April for the Northwest, South Central, Central Highlands, and South, in May and June for all subregions, and in July and August for only the Red River Delta subregion. This suggests that ENSO can provide the potential for improving seasonal climate forecasts and mitigating natural disaster risks for the community.

Integrated design optimization method for novel vapour-compression-cycle-based environmental control systems

The aircraft Environmental Control System (ECS) is the primary consumer of non-propulsive power at cruise conditions, hence, its performance optimization is crucial for the reduction of specific fuel consumption. A novel integrated system design optimization method is presented: thermodynamic cycle, component sizing and working fluid are taken into account simultaneously. This method was applied to the ECS of large rotorcraft based on a Vapour Compression Cycle system electrically driven by a high-speed centrifugal compressor. Steady-state and lumped parameter system component models have been developed using the Modelica acausal modelling language. The optimization design framework consists of an in-house code, featuring a Python-Modelica interface. The study case refers to a critical operating condition: the helicopter is on the ground during a hot and humid day. The working fluid is R-134a. The multi-objective optimization targets the maximization of the system efficiency and the minimization of system weight. The results show that more efficient systems can be designed only with heavier components. The design feasibility of high-speed centrifugal compressors is demonstrated. The advantage of an integrated system design optimization framework for complex energy systems is proved, allowing for the analysis of the impact of both component design and working fluid on system performance.

Colorful low-emissivity paints for space heating and cooling energy savings

Space heating and cooling consume ~13% of global energy every year. The development of advanced materials that promote energy savings in heating and cooling is gaining increasing attention. To thermally isolate the space of concern and minimize the heat exchange with the outside environment has been recognized as one effective solution. To this end, here, we develop a universal category of colorful low-emissivity paints to form bilayer coatings consisting of an infrared (IR)-reflective bottom layer and an IR-transparent top layer in colors. The colorful visual appearance ensures the aesthetical effect comparable to conventional paints. High mid-infrared reflectance (up to ~80%) is achieved, which is more than 10 times as conventional paints in the same colors, efficiently reducing both heat gain and loss from/to the outside environment. The high near-IR reflectance also benefits reducing solar heat gain in hot days. The advantageous features of these paints strike a balance between energy savings and penalties for heating and cooling throughout the year, providing a comprehensive year-round energy-saving solution adaptable to a wide variety of climatic zones. Taking a typical midrise apartment building as an example, the application of our colorful low-emissivity paints can realize positive heating, ventilation, and air conditioning energy saving, up to 27.24 MJ/m2/y (corresponding to the 7.4% saving ratio). Moreover, the versatility of the paint, along with its applicability to diverse surfaces of various shapes and materials, makes the paints extensively useful in a range of scenarios, including building envelopes, transportation, and storage.

Managing vegetation for stronger cooling efficiency during hot days in the Arabian Peninsula

The growth of vegetation in desert areas is expected to cause considerable changes to the local climate. Compared to bare ground desert, the balance of different processes related to vegetation such as reduced albedo and increased evapotranspiration can either warm up or cool down the surface climate. Quantifying these changes is essential for impact assessments of climate mitigation and adaptation measures, especially in regions increasingly hit by heat waves such as the Arabian Peninsula. In this respect, the analysis of in situ observations is challenging owing to limited data, uneven vegetation distribution, complex terrain, and other confounding factors. Thus, this study, using long-term satellite data at the daily temporal resolution, estimates the impact of vegetation on land surface temperature for several agricultural regions in the Kingdom of Saudi Arabia. Results demonstrate that managed vegetation has a significant cooling effect during the day and particularly during hot weather events, reducing the highest temperatures by > 5 °C. During heat waves, managed vegetation can provide an additional cooling effect of about 3 °C (2 to 4 °C depending on the location). This effect is robustly assessed though a tailored statistical indicator that is suitable for application over complex terrain that are found in the Saudi agricultural sites. However, a situation is identified where the vegetation vigor collapsed and the cooling effect vanished, which was possibly related to issues associated with water management sustainability. Thus, herein, this paper discusses several potential solutions to achieve sustainable irrigation among those that were recently proposed in the scientific literature, such as desalinization from renewable energy and land-use change options that could enhance local precipitation. This study supports the decision-making process of the green initiatives undertaken in the Middle East and similar efforts in other arid regions.

Drought metrics and temperature extremes over the Okavango River basin, southern Africa, and links with the Botswana high

AbstractThe Okavango River Basin (ORB), including the World Heritage site Okavango Delta, is a region of high biodiversity projected to suffer increased early summer drying under climate change. Little work has been done on drought over this sensitive region. Here, various drought metrics are analysed over the ORB. These include a cumulative drought intensity index, based on the product of maximum temperature anomaly and maximum duration of a dry spell, and the Standardized Precipitation‐Evapotranspiration Index. Strong gradients in dry spell and hot day frequencies shift south over the ORB from August to November as the tropical rain‐belt moves increasingly south of the equator, the Congo Air Boundary declines and the Botswana High strengthens and moves southwestwards. By December, the tropical gradient in dry spell frequencies has vanished while that across the Limpopo River and southern ORB region, where the Botswana High is centred, is prominent. sub‐seasonal analyses highlight October–November 2013–2021 as particularly dry and hot over the Okavango Delta region. This dry and hot epoch appears related to a stronger and southward shifted Botswana High and reduced low‐level moisture convergence. On interannual scales, strong relationships were found with the Botswana High and El Niño‐Southern Oscillation (ENSO). The early summer shows a strong drying‐warming trend, related to a significant strengthening of the Botswana High. These trends, together with the Coupled Model Intercomparison Project Phase 6 projected early summer drying over southern Africa, may impact severely on the sensitive ecosystems of the ORB and on agriculture, with important implications for the management of agricultural activities, water resources and biodiversity.